Polyorganosiloxanes have been used as textile treating agents, mold release agents, water repellents, cosmetic ingredients and the like because they impart smoothness and water repellency to substrates which are treated therewith. Among others, organosiloxanes having a high degree of polymerization are very effective in imparting smoothness. While surfactants are used in emulsifying polysiloxanes, cationic surfactants such as quaternary ammonium salts are known to improve the adsorption of polysiloxane to substrates. There is an increased demand for the emulsions in which organosiloxanes having a high degree of polymerization are emulsified with the aid of cationic surfactants.
A general polysiloxane emulsifying method is to emulsify and disperse a polysiloxane and a surfactant in water in an emulsifier by applying mechanical shear. No stable emulsions are obtained from organosiloxanes having a high degree of polymerization because their extreme viscosity impedes uniform application of mechanical shear.
One known approach for producing high polymeric polysiloxane emulsions is an emulsion polymerization method of conducting polymerization of a siloxane monomer in emulsion form in the presence of an acid or alkali catalyst as disclosed in JP-B 41-13995 and JP-B 56-38609. In this emulsion polymerization method, however, when cationic surfactants such as quaternary ammonium salts, typically cetyltrimethylammonium chloride are used, the rate of polymerization is very slow, requiring a long period of time until a high degree of polymerization is reached. Even when polymerization is continued for a period of about 150 hours which is considered the commercially permissible maximum, the polysiloxane has been polymerized to only such an extent as to give a viscosity of several ten Pa-s as extracted.
Other known approaches for producing cationic emulsions of high polymeric polysiloxanes include polymerization with silanolate catalysts as disclosed in U.S. Pat. No. 5,504,149 (JP-A 08-104752) and polymerization with ammonium hydroxide catalysts as disclosed in JP-A 2001-106787. The degree of polymerization is insufficient in these methods.
It is also proposed in JP-A 09-137062 and JP-A 10-140480 to produce a high polymeric polysiloxane emulsion with the aid of an anionic surfactant, followed by addition of a cationic surfactant. A problem of stability arises from the combined use of anionic and cationic surfactants.
Polymerization in two stages of different temperature is proposed in JP-A 09-278626, yet taking a long time of polymerization until a high degree of polymerization is reached.